复合衬砌外水压力模型试验研究

为详尽研究复合衬砌外水压力的影响规律，采用自行设计的可拆卸式复合衬砌渗流试验装置，通过改变堵水系统的几何参数、渗透特性以及防排水系统能力等，开展了60，80，100 m三种不同远场高水头环境下复合衬砌堵水与排水系统对衬砌上水压力的影响规律研究。研究结果表明：在全封堵情况下，衬砌上水压力无折减现象，而对于具有一定排水能力的衬砌结构，适当增加灌浆层厚度或减小灌浆层的渗透系数可明显降低作用于衬砌上的外水压力。根据试验数据给出了不同排水面积占比时的外水压力折减系数。研究成果可为实际工程中隧道允许排水量的设计提供参考。

Model test study for external water pressure on composite lining

In order to study the influential law of external water pressure on composite lining in detail, a demountable seepage test equipment for lining was adopted. By changing the geometric parameters and permeability characteristics of water plugging system and the ability of waterproof and drainage system, the influence of water plugging and drainage system of composite lining on water pressure of lining under conditions of 60m 80m and 100m different far field and high water head was studied. The results showed that there was no reduction of water pressure on lining under the condition of full proofing; for a composite lining with a certain drainage capacity, properly increasing the thickness of the grouting reinforced region or reducing the permeability coefficient of the grouting reinforced region could obviously reduce the external water pressure on lining, and the reduction coefficient of external water pressure under different ratio of drainage area is given. The research results can be used as a reference for the design of permissible drainage volume of tunnels.